U.S. patent number 10,648,361 [Application Number 15/219,335] was granted by the patent office on 2020-05-12 for oil debris monitor with sequential coil system and associated algorithms for particle confirmation.
This patent grant is currently assigned to UNITED TECHNOLOGIES CORPORATION. The grantee listed for this patent is UNITED TECHNOLOGIES CORPORATION. Invention is credited to Gregory S. Hagen.
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United States Patent |
10,648,361 |
Hagen |
May 12, 2020 |
Oil debris monitor with sequential coil system and associated
algorithms for particle confirmation
Abstract
A debris monitoring system has a first sensor configured to
generate a first signal indicating a presence of a metallic
particle in a lubrication system. A second sensor is configured to
generate a second signal indicating the presence of a metallic
particle in the lubrication system. A signal processor is
configured to determine a presence of a metallic particle in a
fluid passage based on a comparison of at least the first signal
and the second signal; the second signal being used to verify
accuracy of the first signal. A gas turbine engine and a method for
monitoring a fluid passage for debris are also disclosed.
Inventors: |
Hagen; Gregory S. (Glastonbury,
CT) |
Applicant: |
Name |
City |
State |
Country |
Type |
UNITED TECHNOLOGIES CORPORATION |
Farmington |
CT |
US |
|
|
Assignee: |
UNITED TECHNOLOGIES CORPORATION
(Farmington, CT)
|
Family
ID: |
59416534 |
Appl.
No.: |
15/219,335 |
Filed: |
July 26, 2016 |
Prior Publication Data
|
|
|
|
Document
Identifier |
Publication Date |
|
US 20180030850 A1 |
Feb 1, 2018 |
|
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F02C
3/04 (20130101); G01N 33/2858 (20130101); G01M
15/14 (20130101); F02C 7/06 (20130101); F16N
29/04 (20130101); F01D 21/003 (20130101); F05D
2260/98 (20130101); F05D 2240/35 (20130101); F05D
2220/32 (20130101); F16N 2250/32 (20130101) |
Current International
Class: |
F01D
21/00 (20060101); F02C 7/06 (20060101); G01M
15/14 (20060101); F02C 3/04 (20060101); F16N
29/04 (20060101); G01N 33/28 (20060101) |
Field of
Search: |
;60/39.08 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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102006018964 |
|
Oct 2007 |
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DE |
|
2101330 |
|
Jan 1983 |
|
GB |
|
2016079860 |
|
May 2016 |
|
JP |
|
2015134602 |
|
Sep 2015 |
|
WO |
|
Other References
Electronic Interface for an Inductive Wear Debris Sensor for
Detection of Ferrous and Non-Ferrous Particles. A Thesis Presented
to the Graduate Faculty of the University of Akron. Joseph P. Davis
Dec. 2013. cited by applicant .
A New Oil Debris Sensor for Online Condition Monitoring of Wind
Turbine Gearboxes. Chao Wang, Xiao Liu, Hui Liu and Zhe Chen.
Department of Energy Technology, Aalborg University, Aalborg East,
9220, Denmark. cited by applicant .
On-line and In-line Wear Debris Detectors: What's Out There? Sabrin
Gebarin. A Noria Publication available at:
http://www.machinerylubrication.com/Read/521/in-line-wear-debris-detector-
s. cited by applicant .
European Search Report for European Application No. 17182741.3
dated Aug. 22, 2017. cited by applicant.
|
Primary Examiner: Laurenzi; Mark A
Assistant Examiner: Edwards; Loren C
Attorney, Agent or Firm: Carlson, Gaskey & Olds,
P.C.
Government Interests
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
The subject of this disclosure was made with government support
under Contract No.: N00019-02-C-3003 awarded by the United States
Navy. The government therefore may have certain rights in the
disclosed subject matter.
Claims
The invention claimed is:
1. A debris monitoring system comprising: a first sensor configured
to generate a first signal indicating a presence of a metallic
particle in an oil fluid passage of a lubrication system on a gas
turbine engine as the metallic particle passes the first sensor; a
second sensor configured to generate a second signal indicating the
presence of the metallic particle in the oil fluid passage as the
metallic particle passes the second sensor, the first and second
sensors are arranged in the oil fluid passage; and a signal
processor configured to determine whether the metallic particle is
present in the oil fluid passage based on a comparison of at least
the first signal and the second signal; the second signal being
used to verify accuracy of the first signal.
2. The debris monitoring system of claim 1, wherein the comparison
comprises an assessment of whether a size of a particle indicated
by an amplitude of said first signal matches a size of a particle
indicated by an amplitude of said second signal.
3. The debris monitoring system of claim 1, further comprising a
third sensor configured to generate a third signal, and wherein the
signal processor is configured to include the third signal in the
comparison.
4. The debris monitoring system of claim 1, wherein one of said
first and second sensors is downstream from the other of said first
and second sensors.
5. The debris monitoring system of claim 4, wherein the first
sensor and second sensor are separated by a known distance and the
comparison comprises an assessment of whether the first signal and
second signal are separated by an expected delay consistent with a
single particle carried by a fluid moving at an expected flow
speed.
6. The debris monitoring system of claim 1, wherein the signal
processor is configured to reject simultaneous indications of the
presence of the metallic particle by the first and second signal as
erroneous.
7. The debris monitoring system of claim 1, wherein the signal
processor is configured to calculate an estimated quantity of
debris based on the comparison, and to issue a warning if the
estimated quantity of debris exceeds a threshold.
8. The debris monitoring system of claim 1, wherein the first
sensor and second sensor are in a concentric arrangement at a same
position along the fluid passage.
9. A gas turbine engine comprising: a compressor; a combustor; a
turbine; a lubrication system having an oil fluid passage; and a
debris monitoring system comprising: a first sensor configured to
generate a first signal indicating a presence of a metallic
particle in the oil fluid passage as the metallic particle passes
the first sensor; a second sensor configured to generate a second
signal indicating the presence of the metallic particle in the oil
fluid passage as the metallic particle passes the second sensor,
the first and second sensors are arranged in the oil fluid passage;
and a signal processor configured to determine whether the metallic
particle is present in the oil fluid passage based on a comparison
of at least the first signal and the second signal; the second
signal being used to verify accuracy of the first signal.
10. The gas turbine engine of claim 9, wherein one of said first
and second sensor is downstream from the other of said first and
second sensor.
11. The gas turbine engine of claim 9, wherein the first sensor and
second sensor are separated by a known distance and the comparison
comprises an assessment of whether the first signal and second
signal are separated by an expected delay consistent with a single
particle carried by a fluid moving at an expected flow speed.
12. The gas turbine engine of claim 9, wherein the comparison
comprises an assessment of whether a size of a particle indicated
by an amplitude of said first signal matches a size of a particle
indicated by an amplitude of said second signal.
13. The gas turbine engine of claim 9, wherein the signal processor
is configured to reject simultaneous indications of the presence of
the metallic particle by the first signal and second signal as
erroneous.
14. A method for monitoring an oil fluid passage for debris,
comprising: receiving a first signal from a first sensor arranged
in the oil fluid passage indicating a presence of a metallic
particle in the oil fluid passage of a lubrication system on a gas
turbine engine as the metallic particle passes the first sensor;
checking for a second signal from a second sensor arranged within
the oil fluid passage indicating the presence of the metallic
particle, the second sensor configured to generate the second
signal indicating the presence of the metallic particle in the oil
fluid passage as the metallic particle passes the second sensor;
and if the second signal exists, using the second signal to verify
an accuracy of the first signal.
15. The method for monitoring an oil fluid passage for debris as
recited in claim 14, further comprising estimating a quantity of
debris in the fluid passage.
16. The method for monitoring an oil fluid passage for debris of
claim 15, further comprising issuing a warning if the estimated
quantity of debris in the fluid passage exceeds a threshold.
17. The method for monitoring an oil fluid passage for debris of
claim 14, further comprising using a third signal to verify
accuracy of at least one of the first signal and second signal.
18. The method for monitoring an oil fluid passage for debris of
claim 14, wherein the first sensor and second sensor are separated
by a known distance and the verifying comprises assessing whether
the first signal and second signal are separated by an expected
delay consistent with a single particle carried by a fluid moving
at an expected flow speed.
19. The method for monitoring an oil fluid passage for debris of
claim 14, wherein the verifying includes assessing whether a size
of a particle indicated by an amplitude of the first signal matches
a size of a particle indicated by an amplitude of the second
signal.
20. The method for monitoring an oil fluid passage for debris of
claim 14, wherein the verifying comprises rejecting simultaneous
indications of the presence of the metallic particle by the first
signal and second signal as erroneous.
Description
BACKGROUND
This application relates generally to a debris monitoring system
for an oil distribution system.
Gas turbine engines are known and, typically, utilized to drive
aircraft. A gas turbine engine typically includes a fan section, a
compressor section, a combustor section and a turbine section. Air
entering the compressor section is compressed and delivered into
the combustion section where it is mixed with fuel and ignited to
generate a high-speed exhaust gas flow. The high-speed exhaust gas
flow expands through the turbine section to drive the compressor
and the fan section. The compressor section typically includes low
and high pressure compressors, and the turbine section includes low
and high pressure turbines. More recently, gas turbine engines have
used gear reductions to allow their fan sections to rotate at
different speeds than their turbine sections.
Oil lubrication systems have historically been used to improve the
operation of machinery such as gas turbine engines. Metallic debris
in an oil lubrication system may indicate impending component
failure, so timely discovery of debris in the oil can contribute to
the performance and longevity of a machine. Routine manual
inspection of oil distribution systems has been employed, but more
recently automatic, condition based oil debris monitoring systems
have been discovered to be simpler and less time consuming.
One known oil debris monitoring system uses a sensor having a coil
on an oil line configured to provide a signal upon detecting a
magnetic disruption consistent with metallic debris in the oil
line. Such sensors are susceptible to generating false positives
because available signal processing technology is sometimes unable
to distinguish electromagnetic noise in the environment from
debris. Faults in oil debris monitoring system hardware have
further contributed to false positive signals.
False positive signals may result in unneeded maintenance
downtime.
SUMMARY
In a featured embodiment, a debris monitoring system has a first
sensor configured to generate a first signal indicating a presence
of a metallic particle in a lubrication system. A second sensor is
configured to generate a second signal indicating the presence of a
metallic particle in the lubrication system. A signal processor is
configured to determine a presence of a metallic particle in a
fluid passage based on a comparison of at least the first signal
and the second signal; the second signal being used to verify
accuracy of the first signal.
In another embodiment according to the previous embodiment, the
comparison comprises an assessment of whether a size of a particle
indicated by an amplitude of the first signal matches a size of a
particle indicated by an amplitude of the second signal.
In another embodiment according to any of the previous embodiments,
a third sensor is configured to generate a third signal, and
wherein the signal processor is configured to include the third
signal in the comparison.
In another embodiment according to any of the previous embodiments,
one of the first and second sensors is downstream from the other of
the first and second sensors.
In another embodiment according to any of the previous embodiments,
the first sensor and second sensor are separated by a known
distance and the comparison comprises an assessment of whether the
first signal and second signal are separated by an expected delay
consistent with a single particle carried by a fluid moving at an
expected flow speed.
In another embodiment according to any of the previous embodiments,
the signal processor is configured to reject simultaneous
indications of the presence of a metallic particle by the first and
second signal as erroneous.
In another embodiment according to any of the previous embodiments,
the signal processor is configured to calculate an estimated
quantity of debris based on the comparison, and to issue a warning
if the estimated quantity of debris exceeds a threshold.
In another embodiment according to any of the previous embodiments,
the first sensor and second sensor are in a concentric
arrangement.
In another featured embodiment, gas turbine engine has a
compressor, a combustor, a turbine and a lubrication system. A
debris monitoring system has a first sensor configured to generate
a first signal indicating a presence of a metallic particle in the
lubrication system. A second sensor is configured to generate a
second signal indicating the presence of a metallic particle in the
lubrication system. A signal processor is configured to determine a
presence of a metallic particle in a fluid passage based on a
comparison of at least the first signal and the second signal; the
second signal being used to verify accuracy of the first
signal.
In another embodiment according to the previous embodiment, one of
the first and second sensor is downstream from the other of the
first and second sensor.
In another embodiment according to any of the previous embodiments,
the first sensor and second sensor are separated by a known
distance and the comparison comprises an assessment of whether the
first signal and second signal are separated by an expected delay
consistent with a single particle carried by a fluid moving at an
expected flow speed.
In another embodiment according to any of the previous embodiments,
the comparison comprises an assessment of whether a size of a
particle indicated by an amplitude of the first signal matches a
size of a particle indicated by an amplitude of a the second
signal.
In another embodiment according to any of the previous embodiments,
the signal processor is configured to reject simultaneous
indications of the presence of a metallic particle by the first
signal and second signal as erroneous.
In another featured embodiment, a method for monitoring a fluid
passage for debris including receiving a first signal from a first
sensor indicating a presence of a metallic particle, checking for a
second signal from a second sensor indicating the presence of the
metallic particle, and if a second signal exists, using the second
signal to verify an accuracy of the first signal.
In another embodiment according to the previous embodiment, a
quantity of debris in the fluid passage is estimated.
In another embodiment according to any of the previous embodiments,
a warning is issued if the estimated quantity of debris in the
fluid passage exceeds a threshold.
In another embodiment according to any of the previous embodiments,
a third signal is used to verify accuracy of at least one of the
first signal and second signal.
In another embodiment according to any of the previous embodiments,
the first sensor and second sensor are separated by a known
distance and the verifying comprises assessing whether the first
signal and second signal are separated by an expected delay
consistent with a single particle carried by a fluid moving at an
expected flow speed.
In another embodiment according to any of the previous embodiments,
the verifying includes assessing whether a size of a particle
indicated by an amplitude of the first signal matches a size of a
particle indicated by an amplitude of the second signal.
In another embodiment according to any of the previous embodiments,
the verifying comprises rejecting simultaneous indications of the
presence of a metallic particle by the first signal and second
signal as erroneous.
Although the different examples have the specific components shown
in the illustrations, embodiments of this disclosure are not
limited to those particular combinations. It is possible to use
some of the components or features from one of the examples in
combination with features or components from another one of the
examples.
These and other features disclosed herein can best be understood
from the following specification and drawings, the following of
which is a brief description.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1A schematically shows an embodiment of a commercial gas
turbine engine.
FIG. 1B schematically shows an embodiment of a military gas turbine
engine.
FIG. 2 is a schematic representation of a fluid distribution
system.
FIG. 3A schematically shows a debris monitoring system according to
one embodiment.
FIG. 3B schematically shows a debris monitoring system according to
another embodiment.
FIG. 4 is a plot showing signals from sensors.
FIG. 5A shows a flowchart of a comparison of signals.
FIG. 5B shows a flowchart of a determination of whether to issue a
warning.
FIG. 6 schematically shows a debris monitoring system according to
a third embodiment.
FIG. 7A schematically shows a debris monitoring system according to
a fourth embodiment.
FIG. 7B schematically shows a debris monitoring system according to
a fifth embodiment.
DETAILED DESCRIPTION
FIG. 1A schematically illustrates a gas turbine engine 20 as
typically used in a commercial aircraft. The gas turbine engine 20
is disclosed herein as a two-spool turbofan that generally
incorporates a fan section 22, a compressor section 24, a combustor
section 26 and a turbine section 28. Alternative engines might
include an augmenter section (not shown) among other systems or
features. The fan section 22 drives air along a bypass flow path B
in a bypass duct defined within a nacelle 15, while the compressor
section 24 drives air along a core flow path C for compression and
communication into the combustor section 26 then expansion through
the turbine section 28. Although depicted as a two-spool turbofan
gas turbine engine in the disclosed non-limiting embodiment, it
should be understood that the concepts described herein are not
limited to use with two-spool turbofans as the teachings may be
applied to other types of turbine engines including three-spool
architectures.
The exemplary engine 20 generally includes a low speed spool 30 and
a high speed spool 32 mounted for rotation about an engine central
longitudinal axis X relative to an engine static structure 36 via
several bearing systems 38. It should be understood that various
bearing systems 38 at various locations may alternatively or
additionally be provided, and the location of bearing systems 38
may be varied as appropriate to the application.
The low speed spool 30 generally includes an inner shaft 40 that
interconnects a fan 42, a first (or low) pressure compressor 44 and
a first (or low) pressure turbine 46. The inner shaft 40 is
connected to the fan 42 through a speed change mechanism, which in
exemplary gas turbine engine 20 is illustrated as a geared
architecture 48 to drive the fan 42 at a lower speed than the low
speed spool 30. The high speed spool 32 includes an outer shaft 50
that interconnects a second (or high) pressure compressor 52 and a
second (or high) pressure turbine 54. A combustor 56 is arranged in
exemplary gas turbine 20 between the high pressure compressor 52
and the high pressure turbine 54. A mid-turbine frame 57 of the
engine static structure 36 is arranged generally between the high
pressure turbine 54 and the low pressure turbine 46. The
mid-turbine frame 57 further supports bearing systems 38 in the
turbine section 28. The inner shaft 40 and the outer shaft 50 are
concentric and rotate via bearing systems 38 about the engine
central longitudinal axis X which is collinear with their
longitudinal axes.
The core airflow is compressed by the low pressure compressor 44
then the high pressure compressor 52, mixed and burned with fuel in
the combustor 56, then expanded over the high pressure turbine 54
and low pressure turbine 46. The mid-turbine frame 57 includes
airfoils 59 which are in the core airflow path C. The turbines 46,
54 rotationally drive the respective low speed spool 30 and high
speed spool 32 in response to the expansion. It will be appreciated
that each of the positions of the fan section 22, compressor
section 24, combustor section 26, turbine section 28, and fan drive
gear system 48 may be varied. For example, gear system 48 may be
located aft of combustor section 26 or even aft of turbine section
28, and fan section 22 may be positioned forward or aft of the
location of gear system 48.
The engine 20 in one example is a high-bypass geared aircraft
engine. In a further example, the engine 20 bypass ratio is greater
than about six (6), with an example embodiment being greater than
about ten (10), the geared architecture 48 is an epicyclic gear
train, such as a planetary gear system or other gear system, with a
gear reduction ratio of greater than about 2.3 and the low pressure
turbine 46 has a pressure ratio that is greater than about five. In
one disclosed embodiment, the engine 20 bypass ratio is greater
than about ten (10:1), the fan diameter is significantly larger
than that of the low pressure compressor 44, and the low pressure
turbine 46 has a pressure ratio that is greater than about five
5:1. Low pressure turbine 46 pressure ratio is pressure measured
prior to inlet of low pressure turbine 46 as related to the
pressure at the outlet of the low pressure turbine 46 prior to an
exhaust nozzle. The geared architecture 48 may be an epicycle gear
train, such as a planetary gear system or other gear system, with a
gear reduction ratio of greater than about 2.3:1. It should be
understood, however, that the above parameters are only exemplary
of one embodiment of a geared architecture engine and that the
present invention is applicable to other gas turbine engines
including direct drive turbofans.
A significant amount of thrust is provided by the bypass flow B due
to the high bypass ratio. The fan section 22 of the engine 20 is
designed for a particular flight condition--typically cruise at
about 0.8 Mach and about 35,000 feet (10,668 meters). The flight
condition of 0.8 Mach and 35,000 ft (10,668 meters), with the
engine at its best fuel consumption--also known as "bucket cruise
Thrust Specific Fuel Consumption (`TSFC`)"--is the industry
standard parameter of lbm of fuel being burned divided by lbf of
thrust the engine produces at that minimum point. "Low fan pressure
ratio" is the pressure ratio across the fan blade alone, without a
Fan Exit Guide Vane ("FEGV") system. The low fan pressure ratio as
disclosed herein according to one non-limiting embodiment is less
than about 1.45. "Low corrected fan tip speed" is the actual fan
tip speed in ft/sec divided by an industry standard temperature
correction of [(Tram .degree. R)/(518.7.degree. R)].sup.0.5. The
"Low corrected fan tip speed" as disclosed herein according to one
non-limiting embodiment is less than about 1150 ft/second (350.5
meters/second).
Referring to FIG. 1B, a gas turbine engine 60 as may be used in a
military application includes a fan section 62, a compressor
section 64, a combustor section 66, and a turbine section 68. Air
entering into the fan section 62 is initially compressed and fed to
the compressor section 64. In the compressor section 64, the
incoming air from the fan section 62 is further compressed and
communicated to the combustor section 66. In the combustor section
66, the compressed air is mixed with gas and ignited to generate a
hot exhaust stream 70. The hot exhaust stream 70 is expanded
through the turbine section 68 to drive the fan section 62 and the
compressor section 64. In this example, the gas turbine engine 60
includes an augmenter section 72 where additional fuel can be mixed
with the exhaust gasses 70 and ignited to generate additional
thrust. The exhaust gasses 70 flow from the turbine section 68 and
the augmenter section 72 through an exhaust liner assembly 74.
According to an embodiment of the disclosed invention, a gas
turbine engine 20 or 60 has a lubrication system such as a fluid
distribution system 96 with a series of fluid passages 100, shown
in FIG. 2. In one embodiment, the fluid distribution system 96
distributes oil. Fluid is supplied to machinery 104 through fluid
passages 100 by a supply pump 108 from a reservoir 112. The fluid
is then extracted from the machinery 104 by a scavenge pump 116 and
returned to the reservoir 112. From the schematic representation of
FIG. 2 it can be appreciated that the fluid distribution system 96
can be considered to have a supply side 120, where fluid flows from
the reservoir 112 to the machinery 104, and a scavenge side 124,
where the fluid flows from the machinery 104 to the reservoir 112.
The fluid distribution system 96 has a debris monitoring system 78
with sequential sensors 80a and 80b operating in tandem. The first
sensor 80a and second sensor 80b send a first signal 82a and a
second signal 82b respectively to a signal processor 84, which uses
particle detection algorithms to process the signals 82a and 82b
for the purpose of determining the presence of debris in the
system. The first sensor 80a and the second sensor 80b are
connected by the fluid passage. FIG. 2 shows the debris monitoring
system 78 on the scavenge side 124 of the fluid distribution system
96, but the debris monitoring system 78 could be located on the
supply side 120 or anywhere else as long as they are connected in
serial flow such that the second sensor 80b may be used to verify
signals from the first sensor 80a.
This fluid distribution system 96 provides lubrication to machinery
104 with moving parts. In one example, the machinery 104 may be a
gear reduction, such as gear system 48 of FIG. 1A or other gearbox
or bearing system. In an alternate embodiment, the machinery may
include other gears or bearings such as gear boxes and bearings in
the military engine 60 of FIG. 1B. These may also be within the
definition of machinery 104. In another example, the machinery 104
may include a bearing chamber. In yet another example, the
machinery 104 includes a pump. A worker of ordinary skill in this
art would recognize that the machinery 104 could include any
apparatus that would benefit from a supply of fluid lubricant.
As shown in FIG. 3A, sensors 80a and 80b are connected in serial
flow. The second sensor 80b is downstream from the first sensor 80a
such that when debris or a metallic particle 88 passes by the first
sensor 80a it will subsequently pass by the second sensor 80b. Both
sensors 80a, 80b, may be known sensors able to detect a metallic
particle 88 passing nearby. In an embodiment, at least one of the
sensors 80a, 80b has a field generating coil and a particle sensing
coil. According to one embodiment, both sensors 80a and 80b are the
same type of sensor, but according to a different embodiment they
are different types of sensors. The sensors 80a, 80b each measure a
condition at their respective location. When a metallic particle 88
passes one of the sensors 80a, 80b, the particle 88 will cause a
transient change or disturbance in the condition measured by the
sensors 80a, 80b.
In one embodiment, the sensors 80a and 80b are independent sensors
in tandem and in separate housings 92a and 92b as shown in FIG. 2A.
In another embodiment, the sensors 80a, 80b are two embedded
sensing coils in tandem and are enclosed in a common housing 92 as
shown in FIG. 2B. In an embodiment, the sensors 80a and 80b are
separated by a known distance.
FIG. 4 is a plot of a first measurement 86a and second measurement
86b measured by the first sensor 80a and second sensor 80b,
respectively. The first signal 82a and second signal 82b describe
at least a portion of the first measurement 86a and the second
measurement 86b respectively to the signal processor 84. In an
embodiment, the portion includes the time and waveform of a
disturbance 128, 134. When debris such as a particle 88 passes
sensors 80a, 80b, disturbances 128, 134 in measurements 86a, 86b
are detected. The plot shows a first disturbance 128 in the first
measurement 86a. As can be appreciated, the first disturbance 128
has a waveform with a shape, an amplitude 129, and a length 130.
Likewise, a second disturbance 134 in the second measurement 86b
also has a waveform with a shape, an amplitude 135, and a length
136.
In an embodiment, the sensors 80a, 80b each have a discrete local
processor that monitors their respective measurements 86a, 86b for
disturbances 128, 134 indicative of a metallic particle 88 in the
fluid passage 100. Upon finding such a disturbance 128, 134, the
sensor 80a, 80b will send a signal 82a, 82b to the signal processor
84. In this embodiment, if the signal processor 84 receives a first
signal 82a but never receives a second signal 82b, the signal
processor 84 can determine that the first signal 82a was erroneous.
In this embodiment, the signals 82a, 82b carry details about their
respective disturbances 128, 134. This allows the signal processor
84 to make a comparison of the first signal 82a and the second
signal 82b if the signal processor 84 receives both. From the
comparison, the signal processor 84 can make a determination about
the presence of debris in the fluid passage 100 likely to be more
accurate than a determination based on only one signal 82 from only
one sensor 80.
In another embodiment, the signal processor 84 receives the signals
82a, 82b continuously. In this embodiment, the signal processor 84
monitors the measurements 86a, 86b through the signals 82a, 82b and
the signal processor 84 identifies the disturbances 128, 134.
Using an algorithm, the signal processor 84 can verify accuracy of
the first signal 82a in light of the presence or absence of a
second signal 82b, the information contained within a second signal
82b, or the timing of a second signal 82b.
FIG. 5A shows an example process or algorithm for comparing the
first signal 82a and second signal 82b. The example process
involves the step 140 of receiving at least a first signal 82a and
possibly a second signal 82b followed by the step 144 of verifying
the first signal 82a. The step 144 of verifying involves seeking
confirmation of the first signal 82a from the second signal 82b.
The process concludes by reaching either a determination 148 of
sensor error or a determination 152 of debris in the system. The
step 144 of verification may include several other steps, such as a
step 156 of identifying a first disturbance 128. In embodiments
where a discrete local processor in the first sensor 80a identifies
the first disturbance 128, the step 156 of identifying a first
disturbance will occur before the step 140 of receiving signals and
outside the step 144 of verifying the first signal 82a.
In an example, the step 144 of verifying includes a step 160 of
inquiring as to the presence of a second disturbance 134. If the
signal processor 84 does not receive a second signal 82b indicative
of a disturbance 134, a determination 148 of sensor error can be
reached.
In some embodiments the signal processor 84 may use a flow rate of
the fluid to further refine its comparison. In some embodiments,
the flow rate of the fluid is detected by a flow rate sensing
system. In other embodiments, the flow rate of the fluid is
approximated in view of the functional limits of the fluid
distribution system 96. The signal processor 84 could estimate an
expected delay 138 between when a particle 88 carried by fluid
moving at the flow rate would pass a first sensor 80a and second
sensor 80b. The step 144 of verifying may include a step 164 of
assessing whether the first disturbance 128 and the second
disturbance 134 are separated by the expected delay 138. If the
second disturbance 134 occurs too soon or too late after the first
disturbance 128, a determination 148 of sensor error can be
reached. For example, if the first disturbance 128 and second
disturbance 134 occur simultaneously, the signal processor 84 can
conclude that at least one of the sensors 80a or 80b delivered a
false positive.
In some embodiments, the signal processor 84 can examine the
waveforms of the first disturbance 128 and second disturbance 134
to draw conclusions about characteristics of a particle 88 that
could have cause the disturbances 128, 134. In an example, the
shapes, amplitudes 129, 135, or lengths 130, 136 of the
disturbances 128, 134 are compared. If a step 168 of comparing the
waveforms finds that the first disturbance 128 and second
disturbance 134 are consistent such that they seem to have been
caused by a particle 88 having the same characteristics, a
determination 152 of debris in the system could be reached. In the
alternative, if the first disturbance 128 and second disturbance
134 seem to be results of dissimilar particles 88, a determination
148 of sensor error could be reached. The signal processor 84 could
interpret a determination 148 of sensor error here to mean that no
particle 88 exists, or that a particle 88 does exist but has
characteristics between what the first disturbance 128 or second
disturbance 134 alone would indicate.
It should be understood that the steps 156, 160, 164, 168 within
the step 144 of verification could be conducted in a different
order than described above, or a step 144 of verification could
involve fewer than all of the steps 156, 160, 164, 168 described
above without departing from the scope of the disclosure. In an
example, the step 168 of comparing waveforms is conducted before or
at the same time as the step 164 of assessing whether the first
disturbance 128 and second disturbance 134 are separated by an
expected delay 138. In another example, the step 168 of comparing
the waveforms is not conducted at all. Further, different steps
156, 160, 164, 168 within the step 144 of verification may be
performed by different processors. For example, in an embodiment,
the first sensor 80a has a discrete local processor that performs
the step 156 of identifying the first disturbance 128 and the
second sensor 80b has a discrete local processor that identifies
the second disturbance. In this embodiment, the step 156 of
identifying a first disturbance 128 in the first signal 82a will
occur before the step 140 of receiving signals and outside the step
144 of verifying the first signal 82a.
In an embodiment, the signal processor 84 can issue a warning
according to a process shown in FIG. 5B. The signal processor 84
uses the comparison of the signals 82a and 82b to track individual
particles 88 for a step 172 of estimating a total quantity of
debris or debris content. The signal processor then conducts the
step 176 of comparing the estimated quantity of debris to a
threshold. The signal processor 84 issues 181 a warning if the
total debris content exceeds the threshold and does not issue 185 a
warning if the debris content does not exceed the threshold. In an
embodiment, the warning is an indication that maintenance is
suggested. For example, the warning could indicate that part of the
machinery 104 lubricated by the fluid distribution system 96 is
failing.
An additional embodiment shown in FIG. 6 has a third sensor 80c.
The third sensor 80c sends a third signal 82c that the signal
processor 84 can use to further refine its results. A debris
monitoring system 78 could have even more sensors without departing
from the scope of the disclosure.
While the downstream sensor 80b is disclosed as used to verify the
upstream sensor's 80a signal 82a, the upstream sensor 80a could
alternatively be used to verify the downstream sensor's 80b signal
80b. Further, though the sensors 80a, 80b are depicted as serially
connected in relatively upstream and downstream locations, the
sensors 80a, 80b could be at the same location without departing
from the scope of the disclosure. In an example embodiment of a
debris monitoring system 178 depicted in FIG. 7A, a first sensor
180a and second sensor 180b are arranged concentrically at the same
location in a housing 192. The first sensor 180a and second sensor
180b communicate a first signal 182a and second signal 182b,
respectively, to a signal processor 184. In another example debris
monitoring system 278 depicted in FIG. 7B, a first sensor 280a and
second sensor 280b are arranged in parallel and followed by a third
sensor 280c. The first sensor 280a, second sensor 280b, and third
sensor 280c are respectively embedded in a first housing portion
292a, a second housing portion 292b, and third housing portion
292c. Fluid passing the first sensor 280a or second sensor 280b is
communicated to the third sensor 280c enabling a signal processor
284 to use a third signal 282c to verify accuracy of a first signal
282a and second signal 282b.
The signal 82a, 82b could be a discrete signal and only generated
when a particle 88 passes. Alternatively, the signal 82a, 82b could
be generated continuously, and a disturbance 128, 134 could be
generated by a particle 88.
While the embodiments shown above are in a gas turbine engine, the
system disclosed herein may have applications in other lubrication
applications.
Although an example embodiment has been disclosed, a worker of
ordinary skill in this art would recognize that certain
modifications would come within the scope of this disclosure. For
that reason, the following claims should be studied to determine
the scope and content of this disclosure.
* * * * *
References